Case Studies - Mechanical Design

Case Study - Precision Mechanical Design of Wafer Lift Pin Assembly

The client, nLine Corp., had a requirement for a Z axis stage assembly to provide vertical motion during wafer handling on a semiconductor tool. The challenge was the available space. The assembly would be mounted inside of an irregular space between the structural ribs of the wafer chuck. This creative (and patentable) mechanism design was successfully executed using linear bearings, a creative four-bar linkage, nesting elements and precision machining. All of this was designed to maintain an ultra-low profile to satisfy the packaging envelope. The wafer lift pin assembly was actuated by a clean room pneumatic cylinder. The pneumatic design, especially tubing routing, needed to be minimized, again for space constraints. This was accomplished through means of integrated plumbing machined into the lift platform to feed each of the vacuum ports supporting the wafer.

Precision mechanical design of wafer lift pin assembly, with pneumatic design. Shown with the mechanism extended.

Engineering prototype model with full pneumatic and vacuum design features. Shown collapsed in rest position.

Mechanical Design
Volume production version of precision mechanical design with fully integrated pneumatics - air cylinder removed.

Case Study - Mechanical Design of Precision Alignment System and Hydraulic System for XY Theta Stages

The client, Microelectronics and Computer Technology Corporation - MCC, was the first, and at one time one of the largest, computer industry research and development consortium in the United States. The task of wafer level known good die (WL/KGD) required research and development tools to assess competing options for testing wafers. The challenge was the successful interconnection of tens of thousands of I/O's on a single wafer. Concurrent Design was contracted to develop a means of securing a test coupon (test head) and interfacing an opposing wafer. Each half of the system was to be aligned and then 8 ounces of compression force per I/O point was required. We developed a custom XY theta stage and custom wafer chuck design. Each stage was specified to support over 20,000 pounds (10 tons) of pressure. A hydraulic system was designed with an in-line load cell to allow for adjusting the pressure to within 20 pounds. A vision system was used to align the two stages.

Mechanical Design
Precision mechanical design of a custom high thrust load XY theta stage. Wafer chuck is shown in foreground and wafer test coupon at left with interface board.

Mechanical Design
Vision system (right) allowed for alignment of wafer stage and test head. Hydraulic system (left) was operated within 0.1% of 10 ton full-scale system load. Up to 20,000 I/O's were addressable.

Case Study - Mechanical Design of Factory Tools for Exercising Robots

The client is a manufacturer of semiconductor equipment, including equipment front end modules (EFEM / FEM). This semiconductor equipment provides for robotic based materials handling of the wafer. In the manufacturing assembly environment it is desirable to exercise the robot functionality. Multiple mechanical designs were developed for assorted front end module products to emulate the load ports which might be attached in an actual operational environment. One design simulated four load ports with kinematic mount (kinematic couplings) for wafer FOUP's (added as desired). Another mechanical design allowed placing wafers in multiple vertical and horizontal attitudes. This would simulate handling during chemical mechanical planarization (or chemical mechanical polishing, CMP). Each tool allowed the robot to emulate all possible real-world scenarios. All factory tools provided mechanism design for securing the tool accurately.

Mechanical Design
Mechanical design of robot simulation exercise tool. This tool works with a CMP front end and allows both horizontal and vertical wafer attitudes to be exercised.

Mechanical Design
Mechanism design detail - all factory tools engage to the product within tight tolerances. Six degrees of freedom are addressed. Detail view of mechanical actuator that locks the tool in position during operation.

Mechanical Design
Mechanical design of robot exercise tool. This factory tool locates up to four wafer FOUP's (carriers) to be mounted (kinematic mount) giving the robot complete flexibility during the factory debug exercises.

Case Study - Mechanical Design for Person Guided Vehicle (PGV)

The client, Jenoptik Infab, is a manufacturer of semiconductor equipment. As a precursor to an automated guided vehicle (AGV), the client commissioned a person guided vehicle (PGV). This would allow delivery of wafer FOUP's (carriers) within a semiconductor fab without touching the wafer or the carrier. The reason for this is the high value placed on a full wafer FOUP near the end of the process line. The PGV would acquire or deliver one FOUP from either of two positions. Extensive mechanical sensing was provided for mechanical interlock, thus allowing only the correct action. Electrical sensing was disallowed. All power input was manual. The system was designed to SEMI standards. This system was also the driver for establishing new SEMI standards for the alignment of load ports to PGV style interfaces.

Mechanical Design
Mechanical detail design of person guided vehicle - exploded CAD view showing mechanism design with belt drive, sensor cams, switch linkages and mechanical interlocks.

Mechanical Design
Alpha prototype of person guided vehicle (PGV). One FOUP (forward opening universal pod) is shown. All inputs (power and signal) are mechanical.

Mechanical Design
Mechanical design of beta prototype PGV. Mechanical sensors at base provide locating features to the load port.

For any project requiring complex detailed design of robust machine elements, Concurrent Design provides complete mechanical engineering design services, from concept, analysis, and machine design / tool design to documentation and build.